The Spatial Autocorrelation of Risk to Food Shortfall across Prehistoric Landscapes in the Southwestern United States

Through the Long-Term Vulnerability and Transformation Project at Arizona State University, our research explores the relationship between ecological and social diversity and how these measures of diversity relate to vulnerability to food shortfall in our archaeological case studies. One piece of understanding the vulnerability to failing to produce enough food is defining the risk factors that may limit crop production on a given landscape. Multiple complex socioecological variables need to be considered when defining how prehistoric communities in the Southwestern United States mediated this risk of agricultural failure. Using large spatial archaeological, historical, and ecological datasets in a GIS database, ecological risk factors are mapped and defined for each case study to understand how often different patches of the landscape may fail to produce crops across space and time. Focusing on one of our case studies – the Zuni region in New Mexico – this poster will present how to model the ecological variables that may limit crop production in this region and define how the spatial autocorrelation of risk varies across the Zuni region during different climatic regimes. By creating this ecological “risk landscape,” we can then begin to address the social strategies, such as storage or reliance on social networks, which were employed across the American Southwest when faced with food shortfall.

The Spatial Autocorrelation of Risk to Food Shortfall across Prehistoric Landscapes in the Southwestern United States

Through the Long-Term Vulnerability and Transformation Project at Arizona State University, our research explores the relationship between ecological and social diversity and how these measures of diversity relate to vulnerability to food shortfall in our archaeological case studies. One piece of understanding the vulnerability to failing to produce enough food is defining the risk factors that may limit crop production on a given landscape. Multiple complex socioecological variables need to be considered when defining how prehistoric communities in the Southwestern United States mediated this risk of agricultural failure. Using large spatial archaeological, historical, and ecological datasets in a GIS database, ecological risk factors are mapped and defined for each case study to understand how often different patches of the landscape may fail to produce crops across space and time. Focusing on one of our case studies – the Zuni region in New Mexico – this poster will present how to model the ecological variables that may limit crop production in this region and define how the spatial autocorrelation of risk varies across the Zuni region during different climatic regimes. By creating this ecological “risk landscape,” we can then begin to address the social strategies, such as storage or reliance on social networks, which were employed across the American Southwest when faced with food shortfall.

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This was an intriguing study with major implications for the current study of resilience. However, because you introduced the idea that the Zuni had social systems or planting behaviors to manage risk, I was left wondering how your team was learning about those practices and whether or not they still exist. How would you answer those 2 questions?

Thanks for your question. Currently, we have another part of our larger LTVTP team working on data concerning social diversity in different aspects of prehistoric life, including household types, household features, ceramics, and other artifacts. We hope that these measures of diversity can help shed some light on how people were communicating across the landscape. We are so lucky across the U.S. Southwest, because our temporal resolution is so good. We already have many studies of how people were communicating and moving across the landscape, as well. Theoretically, these studies can help us understand what networks people were drawing upon prehistorically.

Hi Colleen,
I agree with Professor Pinel that this is an intriguing study; I do wonder about the methodology of using modern rainfall/weather patterns as appropriate data sources for pre-historic conditions. Can you give me more information about how/why this backwards reasoning/extrapolation is appropriate?

The issue of the relevance of modern data to prehistoric case studies is something we have thought about a lot. The reason we decided to go with modern data (and we have plenty of retrodictions to draw upon!) is that we wanted monthly data to really hone in on how growing season precipitation varied across a very fine spatial scale (800 m squared). The retrodicted data just doesn’t give us the resolution, both temporally and spatially, needed to answer our questions.

This is a very interesting integration of social and ecological data. You may not be to this point in the project yet, but I was wondering about the archeological evidence of overproduction in wetter areas or production that could meet the needs of other communities in the dryer areas that had not met their subsistence levels. For example, were there more food storage areas in the wetter areas?

We have a little bit of evidence on a very big spatial scale (i.e., the entire U.S. Southwest). For example, in the Phoenix Basin they irrigated their fields (thus creating an artificially wetter environment to produce a surplus of agricultural goods). There is a little bit of evidence of people in the Phoenix Basin trading up to other areas in the U.S. Southwest, but this could not be relied upon in times of stress. The risk mediations strategies (depending on the spatial scales these changes in precipitation are operating on) likely occurred within a much smaller network. I don’t believe any studies have been done linking storage and higher precipitation, but that is certainly an interesting question to ask!

I think I started to address this in my response to Gary below, but I think it certainly can be applied in dealing with environments that we see as marginal. People in the prehistoric U.S. Southwest created ingenious social and ecological strategies to produce a crop in most years to support large pueblos of hundreds of rooms. I believe that these strategies (including diversifying areas where we farm, investment in storage, etc.) can help inform agricultural practices today.

I think I started to address this in my response to Gary below, but I think it certainly can be applied in dealing with environments that we see as marginal. People in the prehistoric U.S. Southwest created ingenious social and ecological strategies to produce a crop in most years to support large pueblos of hundreds of rooms. I believe that these strategies (including diversifying areas where we farm, investment in storage, etc.) can help inform agricultural practices today.

Colleen, You’re engaged in some interesting work and I really like your poster. I will ask you a question that I like to pose to people studying system resilience in the context of the distant past – how if at all can your work help us interesting the thresholds of change in a modern-day desert environment and help us understand social strategies for coping with change? Many thanks, g

Thanks for your question. I think farmers in the desert U.S. Southwest were highly adapted to produce a good crop in regions that are considered otherwise unfarmable today (see the NRCS classifications on “arable soils” – nearly none of them are classified as such, despite the presence of prehistoric fields in the area!). I think these farmers can teach us strategies to mediate risk in a marginal environment concerning precipitation and using a variety of environments (that we today normally do not consider using).

Hi Colleen, Found your presentation very clear as you are very articulate… thanks! It might have helped me if you had included visuals of the region or of the maps in the video… In any case I learned a lot. Thanks